1. Field of the Invention
The present invention relates to a zero insertion force (ZIF) socket, and especially to a ZIF socket having a single-point driving mechanism which drives a cover of the socket to move smoothly with respect to a base thereof in opposite directions from one driving point thus rendering the socket in either a closed status or an open status.
2. The Prior Art
Conventional zero insertion force (ZIF) sockets normally comprise a cover defining a plurality of upper passageways therein and slidably engaging with a base having a corresponding number of lower passageways retaining contacts therein. The upper passageways and the lower passageways are in constant communication with each other when the cover is moved with respect to the base. A cam is received in a space defined between the cover and the base and operative to move the cover with respect to the base thereby positioning the socket at either an open status ready for insertion of pins of a CPU package or a closed status forcing the pins of the CPU package to abut against the corresponding contacts. When the socket is in the open status, the pins of the CPU package are inserted into the upper passageways and the lower passageways with a substantially zero insertion force, but are not in electrical contact with the contacts retained in the lower passageways. The cam is then operated to drive the cover to move laterally relating to the base thereby urging the pins of the CPU package to electrically connect with the contacts of the base. U.S. Pat. No. 5,730,615 which belongs to the same assignee of this application has disclosed a socket having a cover movably engaged with a base and positioning means including a vertical protrusion on the side face of the base to cooperate with a pair of spaced shallow regions, named front shallow region and rear shallow region, formed in the interior portion of the cover. Therefore, the protrusion of the base may be received within the front shallow region in the cover when the socket is in an open status, and within the rear shallow region when the socket is in a closed status. However, the vertical protrusion on the side face of the base is apt to be worn out due to repeated friction with the inner wall of the shallow regions. If one of the vertical protrusions is worn out, the left one will cause an imbalance thus hindering the normal movement of the cover.
Moreover, a driving mechanism as disclosed in the prior art for driving the cover to move with respect to the base utilizes a screwdriver inserted into slots defined in the cover and the base to drive the cover. Since the slots are defined in expansion sections respectively extended from center portions of front sides of the base and the cover, the driving point is relatively small compared to the front side of the cover. With this structure, the driving force from the screwdriver is not guaranteed evenly distributed in two sides of the cover which may cause the cover to move not smoothly on the base. Additionally, when the user pivots the screwdriver he (she) needs a considerable space for operation and may be prohibited by peripheral components nearby thus causing difficulty.
It is requisite to provide a new socket to solve the above problems.